diff --git a/main.go b/main.go
index 0f756a4..1886a57 100644
--- a/main.go
+++ b/main.go
@@ -1967,7 +1967,7 @@ func flagSetValue(flags []string, name, value string) []string {
 
 func fetchGoEnv() error {
 	out, err := exec.Command("go", "env", "-json",
-		"GOPRIVATE", "GOMOD", "GOVERSION", "GOCACHE",
+		"GOOS", "GOPRIVATE", "GOMOD", "GOVERSION", "GOCACHE",
 	).CombinedOutput()
 	if err != nil {
 		fmt.Fprintf(os.Stderr, `Can't find Go toolchain: %v
diff --git a/scripts/runtime-linknamed-nodeps.sh b/scripts/runtime-linknamed-nodeps.sh
new file mode 100755
index 0000000..9ee9b64
--- /dev/null
+++ b/scripts/runtime-linknamed-nodeps.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+
+# The list of all packages the runtime source linknames to.
+linked="$(sed -rn 's@//go:linkname .* ([^.]*)\.[^.]*@\1@p' $(go env GOROOT)/src/runtime/*.go | grep -vE '^main|^runtime\.' | sort -u)"
+
+# The list of all implied dependencies of the packages above,
+# across all main GOOS targets.
+implied="$(for GOOS in linux darwin windows js; do
+	for pkg in $linked; do
+		GOOS=$GOOS GOARCH=$GOARCH go list -e -deps $pkg | grep -v '^'$pkg'$'
+	done
+done | sort -u)"
+
+# All packages in linked, except those implied by others already.
+# This resulting list is what we need to "go list" when obfuscating the runtime,
+# as they are the packages that we may be missing.
+comm -23 <(
+	echo "$linked"
+) <(
+	echo "$implied"
+)
diff --git a/shared.go b/shared.go
index 9c1bb41..7beda3c 100644
--- a/shared.go
+++ b/shared.go
@@ -39,8 +39,11 @@ type sharedCache struct {
 
 	GOGARBLE string
 
-	// From "go env", primarily.
+	// Filled directly from "go env".
+	// Remember to update the exec call when adding or removing names.
 	GoEnv struct {
+		GOOS string // i.e. the GOOS build target
+
 		GOPRIVATE string
 		GOMOD     string
 		GOVERSION string
@@ -225,6 +228,8 @@ func appendListedPackages(patterns ...string) error {
 	return nil
 }
 
+var listedRuntimeLinknamed = false
+
 // listPackage gets the listedPackage information for a certain package
 func listPackage(path string) (*listedPackage, error) {
 	if path == curPkg.ImportPath {
@@ -248,15 +253,44 @@ func listPackage(path string) (*listedPackage, error) {
 		if ok {
 			return pkg, nil
 		}
-		// TODO: List fewer packages here. std is 200+ packages,
-		// but in reality we should only miss 20-30 packages at most.
-		if err := appendListedPackages("std"); err != nil {
+		if listedRuntimeLinknamed {
+			panic(fmt.Sprintf("package %q still missing after go list call", path))
+		}
+		startTime := time.Now()
+		// Obtained via scripts/runtime-linknamed-nodeps.sh as of Go 1.18beta1.
+		runtimeLinknamed := []string{
+			"crypto/x509/internal/macos",
+			"net",
+			"os/signal",
+			"plugin",
+			"runtime/debug",
+			"runtime/metrics",
+			"runtime/pprof",
+			"runtime/trace",
+			"syscall/js",
+		}
+		var missing []string
+		for _, linknamed := range runtimeLinknamed {
+			switch {
+			case cache.ListedPackages[linknamed] != nil:
+				// We already have it; skip.
+			case cache.GoEnv.GOOS != "js" && linknamed == "syscall/js":
+				// GOOS-specific package.
+			case cache.GoEnv.GOOS != "darwin" && linknamed == "crypto/x509/internal/macos":
+				// GOOS-specific package.
+			default:
+				missing = append(missing, linknamed)
+			}
+		}
+		if err := appendListedPackages(missing...); err != nil {
 			panic(err) // should never happen
 		}
 		pkg, ok := cache.ListedPackages[path]
 		if !ok {
 			panic(fmt.Sprintf("runtime listed a std package we can't find: %s", path))
 		}
+		listedRuntimeLinknamed = true
+		debugf("listed %d missing runtime-linknamed packages in %s", len(missing), debugSince(startTime))
 		return pkg, nil
 	}
 	// Packages other than runtime can list any package,
diff --git a/testdata/scripts/crossbuild.txt b/testdata/scripts/crossbuild.txt
index 68ae66d..b681856 100644
--- a/testdata/scripts/crossbuild.txt
+++ b/testdata/scripts/crossbuild.txt
@@ -8,10 +8,8 @@
 [!arm] env GOARCH=arm
 [arm] env GOARCH=arm64
 
+# A fairly average Go build, importing some std libraries.
 env GOGARBLE='*'
-
-# Link a binary importing net/http, which will catch whether or not we
-# support ImportMap when linking.
 garble build
 
 -- go.mod --
diff --git a/testdata/scripts/gogarble.txt b/testdata/scripts/gogarble.txt
index eafb655..26bee34 100644
--- a/testdata/scripts/gogarble.txt
+++ b/testdata/scripts/gogarble.txt
@@ -71,8 +71,14 @@ var LongString = "some long string to obfuscate"
 -- stdimporter/main.go --
 package main
 
-import "net/http"
+import (
+	"net/http"
+	"runtime/debug"
+)
 
 func main() {
 	http.ListenAndServe("", nil)
+	// debug.WriteHeapDump is particularly interesting,
+	// as it is implemented by runtime via a linkname.
+	debug.WriteHeapDump(1)
 }
diff --git a/testdata/scripts/runtime-related.txt b/testdata/scripts/runtime-related.txt
deleted file mode 100644
index 4f3f6bd..0000000
--- a/testdata/scripts/runtime-related.txt
+++ /dev/null
@@ -1,55 +0,0 @@
-# test that we used all necessary dependencies
-[linux] exec bash runtime-related-tested.sh
-
-env GOPRIVATE=*
-garble build
-
--- runtime-related.sh --
-for GOOS in linux darwin windows; do
-	skip="|macos"
-	if [[ $GOOS == "darwin" ]]; then
-		skip=""
-	fi
-
-	GOOS=$GOOS go list -deps $(sed -rn 's@//go:linkname .* ([^.]*)\.[^.]*@\1@p' $(go env GOROOT)/src/runtime/*.go | grep -vE '^main|^runtime\.|js'$skip) runtime || exit 1
-done | sort -u
-
--- runtime-related-tested.sh --
-# get all runtime-related deps
-related=$(bash runtime-related.sh) || exit 1
-
-# get all tested deps
-tested=$(for GOOS in linux darwin windows; do GOOS=$GOOS go list -deps || exit 1; done | sort -u)
-
-# remove all tested deps from the runtime-related deps 
-output=$(echo "$related" | grep -Fvx -e "$tested")
-
-# output should be empty if all runtime-related deps are tested
-[[ -z "$output" ]] || (echo "$output" && exit 1)
-
--- go.mod --
-module test/main
-
-go 1.17
-
--- main.go --
-package main
-
-import (
-	"net/http/pprof"
-	"os/signal"
-	"plugin"
-	"runtime/debug"
-	"runtime/metrics"
-	"text/tabwriter"
-)
-
-// This program imports all runtime-related dependencies (proven by runtime-related-tested.sh)
-func main() {
-	_ = tabwriter.AlignRight
-	signal.Ignore()
-	_ = plugin.Plugin{}
-	_ = pprof.Handler("")
-	_ = debug.GCStats{}
-	metrics.All()
-}